Shotgun barrel



Sept. 15, 1936. G. s. LEWIS 2,054,132

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i Q \g H I n Patented Sept. 15, 1936 SHOTGUN BARREL George S. Lewis, Springfield, Masa, assignor to Winchester Repeating Arms Company, New

Haven, Conn., a corporation of Maryland Application January 9, 1933, Serial No. 650,752

2 Claims. (01- 2-79) This invention relates to an improvement in firearm barrels and particularly to so-called "choke-bored barrels for firearms of the type designed for simultaneously discharging a plurality of pellets and commonly referred to as shotguns.

It is well known to those skilled in the art to which my invention relates that various modifications of shotgun barrels, from straight cylindrical bores to barrels having a maximum degree of constriction (commonly known as choke") at or adjacent the muzzle thereof. will serve to vary the characteristics of the shot pattern produced, both as regards the size of pattern and the uniformity of the dispersion of the shots within the boundaries of such patterns. Heretofore, attempts to secure the desired degree of one particular pattern characteristic have often resulted in a-loss with respect to the other of said characteristics.

One of the objects of my present'i-nvention is to provide a shotgun barrel which may be relied upon to reproduce from shot to shot substantially the same character of pattern at a given range.

Another object of my invention is to provide a shotgun barrel which will discharge the shot in such manner as to give desired openness of shot pattern combined with uniformity of shot dispersion in such pattern.

Other objects will appear to those skilled in the art from the following, taken in conjunction with the accompanying drawing and the appended claims.

In the accompanying drawing:

Fig. 1 is a view in side elevation of a shotgun equipped with a barrel embodying my invention;

Fig. 2 is a central, longitudinal, schematic, sectional view of the muzzle-portion of the barrel thereof shown on an enlarged scale; and

Fig. 3 is a view corresponding to Fig. 2 but showing the constricting-taper and expandingtaper in the bore thereof rough finished, prior to a subsequent finishing operation.

In the particular shotgun barrel herein chosen for the illustration of my invention, the barrel I is shown as a feature of a shotgun which, in brief, includes a receiver II and butt-stock l2. Such a shotgun herein requires no detailed description other than such as relates to the bore of the barrel 10 thereof adjacent its muzzle end.

Adjacent its muzzle end ill the barrel i0 is provided internally with two tapered portions l3 and II respectively tapering in opposite directions and having their respective smaller diameters joined at a point substantially at i 5.

The taper l3 merges at its rear end into the full diameter of the bore l8 of the barrel and from such point of juncture tapers forwardly and inwardly and may properly be described as a constricting-taper leading up to the point Ii, which 6 latter constitutes the point of maximum constriction or choke in the bore of the barrel. Preferably the diameter at the point of maximum constriction or choke I is not less than ninety per cent (90.0%) of the full diameter of the bore 10 I6. The taper i4 joins the constricting-taper i 3 at the point l5 as before described and slopes forwardly and outwardly from such point. and may be characterized as an expanding-taper.

By reference to Fig. 2, it will be noted that the constricting-taper i3 and the expanding-taper M are oined at I 5 by a slightly-curved throatportion, which in a technical sense provides a substantially non-cylindrical area between the two said tapers so that, as herein shown, the constricting-taper l3 and expanding-taper it are joined together without the interposition between them of any appreciable cylindrical portion.

In the accompanying drawing, the slope of the constricting-taper l3 and expanding-taper I4 is exaggerated for purposes of clarity of illustration, and I have discovered that the performance of the barrel l0 upon discharging shot therethrough is largely dependent upon the degree of taper of the expanding-taper I4. I have ascertained that highly desirable results may be assured if the expanding-taper i4 referred to has a slope per inch of not less than .0035" and not more than .0075", though departures may be made under my invention, from the figures just given. A taper of .005" has proven most satisfactory.

Preferably, in the manufacture of shotgun barrels embodying my invention, the bore I5 is provided with the constricting-taper i 3 prior to the creation of the expanding-taper I 4, so that the portion of the bore lying forward of the said constricting-taper is of an internal diameter smaller than the ultimate diameter desired at the point l5.

After the formation of the constricting-taper i3 as above described, the expanding-taper i4 may be formed by suitable cutting tools, such, for instance, as a taper-reamer, and it is obvious that the degree to which such reamer or other tool is projected into the muzzle-end of the barrel l0 will determine the diameter at the point l5 (Fig. 3).

By reference to Fig. 3 it will be seen that should the reamer referred to be projected into the barrel so as to cut along the dotted lines A, the diameter at the point of maximum constriction II will be greater and will be-located slightly to the rear of the point indicated by full lines in Fig. 3.

It will also be seen that by still further advancing the said reamer, the constricting-taper l8 may be completely removed to provide a cylinder-bored barrel having only an expandingtaper, and my invention contemplates the production of a barrel of this character. In practice, however, this effect would preferably be produced by first continuing the full diameter. l6 through the full length of the barrel before producing the expanding-taper M. It follows that the diameter at the rear extremity of the expanding-taper It will thus have a maximum equalling that of the full diameter of the bore l6.

Preferably, after the tapers l3 and it have been formed and joined as above described (Fig. 3), one or. more finishing operations are performed upon the interior of the barrel ,to smooth ,the interior surface of the bore and, incidentally,

to round off the Junction-point between the tapers l3 and M, as shown in Fig. 2.

It will be obvious to those skilled in the art that the order in which the tapers l3 and I4 are produced, as abovedescribed, may be reversed if desired.

From the description above given of the preferred mode of manufacture, it will be apparent that the degree of choke imparted to the barrel It may be conveniently determined by the degree to which the tool forming the second taper penetrates toward the first-formed taper. Under my invention, also, the shotgun barrel, once manufactured, may be conveniently altered, as above described, should such alteration be desired, without undueexpense and without endangering the concentricity of the choke--portion l5 thereof.

Regardless of its mode of manufacture, my improved shotgun barrel may be so internally shaped as to produce a maximum size of shot pattern, despite which it will be found that the shot are distributed throughout such pattern to a degree more uniform than heretofore attained except accidentally. Furthermore, should it be desired to produce a relatively-small pattern at a given range, the same may be eilected in accordance with my invention, and in this instance, also, the

dispersion of the shot throughout the pattern will be of maximum uniformity.

One of the outstanding advantages of my improved gun-barrei resides in the fact that regardless of to what degree the barrel is "choked", at each successive shot the pattern produced will be surprisingly uniform, both as to size of the pattern and distribution of theshot therein. In this connection, it may be stated that one of the major objections to guns of the prior art has been that while it has been occasionally possible to produce open shot-pattern combined with evenness 'of shot-distribution, that both such cfiazacteristics would markedly vary from shot to s o I claim:

1. A shotgun barrel having formed in its bore adjacent the muzzle-end thereof, an inwardlyand-forwardly-sloping constricting-taper having an outwardly-bowed arcuate wall and an outwardly-and-forwardly-sloping expanding-taper; the said tapers joining each other to form a choke and being substantially free at their point of junction of intervening cylindrical surfaces; the outwardly-bowed wall of the said constricting-taper having a substantially-continuous curvature and acting to compress the charge from a shell at a progressively-increasing rate before such charge reaches the said expanding-taper for progressive expansion therein.

2. A shotgun barrel having formed in its bore adJacent its muzzle-end an inwardly-and-forwardly-sloping constricting-taper having an outwardly-bowed arcuate wall and an outwardlyand-forwardly-sloping expanding-taper; the said tapers joining each other to form a choke and being substantially free at their point of junction of intervening cylindrical surfaces, the rear portion of the said outwardly-bowed constrictingtaper merging smoothly into the untapered portion of the bore of the barrel; the outwardlybowed wall of the said constricting-taper having a substantially-continuous curvature and acting to compress the charge from a shell at a progressively-increasing rate before such charge reaches the said expanding-taper for progressive expansion therein.

GEORGE S. LEWIS. 

